AN ANTIIDIOTYPIC ANTIBODY THAT RECOGNIZES THE BETA-ADRENERGIC-RECEPTOR

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Abstract

Antialprenolol rabbit antibodies were fractionated on an acebutolol affinity resin, followed by L-propranolol elution so as to separate a class of binding sites that mimic the beta-adrenergic receptor. Allotype-identicaL rabbits were immunized with this fraction. After 6 mo, antisera exhibited antiidiotypic activity inhibiting [3H]alprenolol binding to the original antibody and to rabbit antiacebutolol antibodies, which had a spectrum of ligand-binding properties identical to the original idiotype. Those antisera demonstrating the original idiotype. Those antisera demonstrating the most potent antiidiotypic activity also blocked [3H]alprenolol binding to the beta-adrenergic receptor of turkey membrane, canine pulmonary membrane, and rat reticulocyte. An idiotype affinity-purified fraction showed similar activity, inhibiting beta-receptor binding with a calculated dissociation constant (KD) of 53 nM. Isoproterenol-mediated adenylate cyclase activity was also inhibited in a competitive manner. The universality of recognition of these antiidiotypic antisera indicate that the three-dimensional structure of a receptor's binding site can be modeled by a subset of an elicited antibody population.

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